Wireless Device Antenna Port Frequency Sub-band Allocation
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Solution Overview
Problem
In wireless communication networks, multi-antenna uplink transmissions face challenges with limited total and per-port transmit power, leading to weak power spectral density, especially under adverse channel conditions, and beamforming may not be feasible or desirable due to antenna separation and phase relation uncertainties.
Innovation Solution
A method where a wireless device transmits signals simultaneously from multiple physical antenna ports, restricting each port to a disjoint frequency sub-band within the frequency bandwidth, allowing higher power spectral density without the need for beamforming, by allocating per-port transmit power only to frequency elements within the associated sub-band.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Power
If multiple physical antenna ports transmit reference signals simultaneously, then the total transmit power increases, but the power spectral density per signal becomes too weak due to power distribution across ports
Solution Approach 1:
The frequency bandwidth is divided into multiple disjoint frequency sub-bands, with each physical antenna port transmitting reference signals only in its assigned sub-band. This segmentation allows the total transmit power to be distributed across multiple ports while maintaining sufficient power spectral density in each sub-band, as each port concentrates its power within a narrower frequency range rather than spreading it across the entire bandwidth.
2Power
If beamforming is used to improve link gain, then the output power and beamforming gain increase, but complications arise from antenna separation and unknown phase relations
Solution Approach 1:
The patent extracts the beamforming function from the reference signal transmission process. By assigning disjoint frequency sub-bands to different antenna ports and eliminating the need for coherent combining across ports, the complex beamforming operations (phase adjustment, amplitude weighting, and spatial filtering) are removed. This simplification eliminates issues related to antenna separation and unknown phase relations while still achieving improved power spectral density through frequency-domain segmentation.
3Adaptability or versatility
If each physical antenna port transmits over the full frequency bandwidth, then the coverage is maximized, but the power spectral density decreases due to power distribution
Solution Approach 1:
The frequency bandwidth is segmented into multiple disjoint sub-bands, with each physical antenna port responsible for transmitting reference signals in its assigned sub-band. This segmentation strategy maintains overall frequency coverage by ensuring that collectively all ports span the full bandwidth, while simultaneously improving power spectral density by concentrating each port's transmit power within its narrower assigned sub-band rather than spreading it across the entire bandwidth.
Data Source
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Figure 3
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AI summary
A wireless device (12) is configured to transmit a signal simultaneously from a group (104) of physical antenna ports (106), based on associating disjoint frequency sub-bands with respective ones of the physical antenna ports (106). The frequency sub-bands collectively span a frequency bandwidth and each physical antenna port (106) supports transmission over the frequency bandwidth and has a per-port transmit power associated therewith. The wireless device (12) is configured to transmit the signal further based on allocating the per-port transmit power of each physical antenna port (106) in the group (104) only to frequency elements of the signal that fall within the frequency sub-band associated with the physical antenna port (106). A radio network node (10) in a network (16) is configured to perform channel estimation based on receiving a reference signal from the wireless device (12) and its channel estimation accounts for channel changes that may appear at the border between two frequency sub-bands.